Petroleum products from oil shale

ABSTRACT

A system for producing petroleum products ( 12 ) from oil shale ( 32 ) includes a kiln line ( 72,152 ) of plural series-connected, substantially horizontally-disposed kilns ( 90,94,104,170,180 ). Crushed oil shale ( 36 ) is advanced through kilns ( 90,94,104,170,180 ) in succession and exhausted from the kiln line ( 72,152 ) substantially freed of hydrocarbons. A heat extraction unit ( 80 ) recovers heat ( 82 ) from hot spent shale ( 78 ). Successive kilns ( 90,94,104,170,180 ) along the advancement of crushed oil shale ( 36 ) are maintained at successively higher temperatures (T 94 ,T 94 ,T 104 ,T 170 ,T 180 ). Pyrolysis is indirectly-driven using kiln-surrounding roasting jackets ( 96,106,182 ), A fuel distinct from hydrocarbons in oil shale ( 32 ), such as natural gas ( 132 ), syngas ( 54 ) from a gasifier ( 48 ), or hydrogen gas ( 62 ) from a separator ( 60 ) provides heat. These combustible gasses are burned in roasting jackets ( 96,106,182 ) or converted by a burner ( 134 ) into hot flue gas ( 136 ) that passes through roasting jackets ( 96,106,182 ). A heated sweep gas ( 142 ) entrains hydrocarbon vapors ( 98,108 ). An acoustic agitator ( 192 ) suppresses clumping of crushed oil shale ( 36 ) A refining unit ( 22 ) proximate the kiln line ( 72,152 ) upgrades into petroleum products ( 12 ) extracted hydrocarbons in vapor ( 74 ) or liquid ( 54 ) states.

BACKGROUND

A. Field of the Invention

The present invention relates generally to the extraction from oil shaleof useful hydrocarbons as petroleum products. More particularly, thepresent invention pertains to systems and methods for deriving refinedpetroleum products directly from oil shale.

B. Background of the Invention

Oil shale reserves are massive, but relatively untapped. Therefore,these reserves represent a promising source of combustible liquidhydrocarbons for use in contemporary societies. The useful hydrocarbonsreside in oil shale in the form of so-called kerogens. Kerogensencompass an intermixed diversity of potentially useful hydrocarbonsthat range in weight from very light and highly volatile to very heavyand resistive to vaporization.

One approach to extracting useful hydrocarbons from oil shale involvesthe application of heat to the oil shale, and ultimately thevaporization and capture of the useful hydrocarbons freed thereby fromthe oil shale. This type of processing is referred to as pyrolysis.Existing pyrolysis technologies utilize processes that are poorlyintegrated, both physically and conceptually. Such systems are not,therefore, capable of producing petroleum products, either of anadequate quality on in a sufficient volume, as to be able to competeeffectively in the marketplace against petroleum products from otherhydrocarbon sources.

SUMMARY OF THE INVENTION

The present invention provides systems and methods that overcomenumerous of the shortcomings in existing approaches to extracting usefulhydrocarbons from oil shale.

It is thus an objective of the present invention to enable petroleumproducts to be derived from oil shale efficiently, thereby to competeeffectively as a marketplace alternative to other sources of combustiblehydrocarbons.

Certain features and advantages of the invention have been generallydescribed in this summary section; however, additional features,advantages, and embodiments are presented herein or will be apparent inview of the drawings, specification, and claims hereof. Accordingly, itshould be understood that the scope of the invention is not to belimited by the particular characterizations presented in this summarysection.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will be made to exemplary embodiments of the present inventionthat are depicted in the accompanying figures. Those figures areintended to be illustrative, rather than limiting. Although the presentinvention is generally described in the context of those embodiments, itis not intended by so doing to limit the scope of the present inventionto the particular features of the embodiments depicted and described.

FIG. 1 is a diagrammatic overview depiction of a system and a methodembodying teaching.

FIGS. 2A and 2B taken together present a detailed diagrammatic depictionof a first embodiment of the system and the method of FIG. 1.

FIG. 3 is a detailed diagrammatic depiction of the apparatus and relatedmethodology associated with one exemplary embodiment of a kiln line ofthe type shown in the system and the method of FIG. 2B.

FIGS. 4A and 4B taken together present a detailed diagrammatic depictionof a second embodiment of the system and the method of FIG. 1.

FIG. 5 is a detailed diagrammatic depiction of the apparatus and relatedmethodology associated with one exemplary embodiment of a kiln line ofthe type shown in the system and the method of FIG. 2B.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the following description, for purpose of explanation, specificdetails are set forth in order to provide an understanding of thepresent invention. The present invention may, however, be practicedwithout some or all of these details. The embodiments of the presentinvention described below may be incorporated in whole or in part into anumber of different systems and methods. Structures, materials, andprocedures are depicted in diagrammatic from, thereby to be illustrativeof structures, materials, and procedures in exemplary embodiments of thepresent invention. Such structures, materials, and procedures are not,therefore, to be used as a pretext by which to obscure broad teachingsof the present invention. Connections between structures, materials, andprocedures depicted in the figures are not intended to be limited todirect connections. Rather, such connections may be modified,re-formatted, or otherwise changed by intermediary elements.

When the specification makes reference to “one embodiment” or to “anembodiment” it is intended mean that a particular feature, structure,characteristic, or function described in connection with the embodimentbeing discussed is included in at least one contemplated embodiment ofthe present invention. Thus, the appearance of the phrase, “in oneembodiment,” in different places in the specification does notconstitute a plurality of references to a single embodiment of thepresent invention.

The methods and systems of the present invention focus on petroleumproducts as the key output, rather than on using any fraction of thatpotential output, for example, to generate electricity for consumptionon site or elsewhere. Toward that end, in one aspect of the presentinvention, the quantity and quality of the process output is optimizedby minimizing the consumption of any of the BTU content of thepotentially useful hydrocarbons in the oil shale being processed; evento obtain heat with which to drive pyrolysis. In some inventiveembodiments, none of the BTU content of the potentially usefulhydrocarbons in the oil shale being processed is used at all.

The employment in a heat source of a fuel other than the usefulhydrocarbons in the oil shale granules being processed has a positiveimpact on the value of the oil vapors produced. The full BTU content ofthe oil shale granules is conserved in those extracted oil vapors. It isthe lighter hydrocarbons that are consumed when oil vapors from oilshale granules are used to drive pyrolysis. As a result of minimizingreliance of the inventive system on the BTU content of oil shale,lighter hydrocarbons in the oil shale granules are preserved, leading tooutput oil vapor that may even take that form of light crude thatrequires only routine upgrading to be converted into useable high-gradepetroleum.

An inventive system is optimally installed and used in proximity to amine or other source of oil shale. The oil shale is processed at acrusher into oil shale granules of about 0.375 inches in diameter. Theseare fed into kilns of the system. There moisture (H₂O) is first removed.Useful hydrocarbons in the form of oil vapors are extracted bypyrolysis. Pyrolysis occurs in a single or in successive stages.Optionally, a sweep gas is used to inhibit combustion of the oil vaporsproduced in the pyrolysis environment, as well as to remove the oilvapors therefrom. Spent shale granules are transported or stored,possibly within the mine from which the oil shale originated.

Oil vapors are processed further at a refining unit. There the extractedhydrocarbons are upgraded into petroleum products, and the petroleumproducts are separated according to predetermined criteria, such asweight, type, and use. It is preferred, but not in all instancesessential, that this distillation and cracking of extracted hydrocarbonsbe performed on site at the kilns, and immediately while the oil vaporscontaining those extracted hydrocarbons emerging from pyrolysis remainhot.

Heat for driving pyrolysis is derived from a variety of fuel, such asnatural gas or coal, either of which is likely to need to be transportedto the site of the system from remote sources.

In an embodiment of a system and method incorporating teachings of thepresent invention and utilizing coal as a source of heat, about one (1)ton of coal is required to process each ten (10) tons of oil shale. Thecoal is pulverized at the site of the system to a fineness of about 200mesh and then converted in a gasifier at the site of the system intosynthetic coal gas, which is conventionally termed “syngas”. Thatsyngas, or syngas imported to the site of the system, is used primarilyor solely for driving pyrolysis of oil shale. Hydrogen (H₂) gas may inaddition be used to supplement the syngas in driving pyrolysis.

In an alternative embodiment of a system and method incorporatingteachings of the present invention that utilizes a different combustiblegas, such as propane, as a source of heat, the combustible gas isconsumed in a burner, and the hot flue gas produced thereby is used todrive pyrolysis. Syngas may also be thusly consumed in a burner tocreate flue gas with which to drive pyrolysis. It may be advantageous touse some of the heat produced in such burners to preheat the sweep gas,if any, used in the system.

Optionally, some of the syngas is processed in a hydrogen separator intohydrogen (H₂) gas, which is employed primarily in the refining unit ofthe system. At the refining unit, hydrogen (H₂) gas is used to upgradeextracted oil vapors into petroleum products. Various weights ofrefined, motor-ready petroleum products can as a result be drawn off atappropriate stages from the refining unit. To optimize the operation ofthe refining unit, light oil vapors and heavy oil vapors may beprocessed there independently at different times.

Pyrolysis occurs in at least a single kiln line of plural, substantiallyhorizontally-disposed, series-connected kilns.

As used herein, the expression “substantially horizontally-disposed”when used to describe a kiln in which oil shale is processed is intendedto refer, both to such kilns as are strictly horizontal in disposition,as well as to such kilns as are relatively gently inclined relative tothe true horizontal at, for example an angle of inclination that is lessthan about 30° to that true horizontal. Generally, the expression“substantially horizontally-disposed” as used herein will refer to theorientation of the lower side of the kiln being described, rather thanto the longitudinal axis, if any, or the upper side of that kiln. A kilnexhibiting a cross-sectional configuration or size that changes alongthe length of the kiln is, therefore, not per se intended to be excludedfrom the from possibly being a substantially horizontally-disposed kilnwithin the context of the present application. Thus also, asubstantially horizontally-disposed kiln is intended herein topotentially include kilns that are stationary and kilns that aremoveable, as in the case of rotatable kilns.

For example, the system and method of the present invention may besatisfactorily be embodied in systems and methods involving kiln linesthat include some or a totality of inclined rotary kilns. Each suchinclined rotary kiln includes an elongated rotating drum having an inputend for receiving oil shale and an output end that is disposed lowerthan the input end and through which processed oil shale is exhausted.

As an inclined rotary kiln is rotated about the longitudinal extentthereof, oil shale being processed in the kiln is tumbled longitudinallythrough the kin. This effect may be facilitated by the interiorconstruction of the kiln by, for example, the attachment ofappropriately oriented vanes to the inner surface of the kiln. In analternate from of such a transport for advancing oil shalelongitudinally through a kin during processing of the oil shale in thekiln, a stationary substantially horizontally-disposed kiln may beprovided with an internal conveyor, such as a chain conveyor, a paddleconveyor, or a bucket conveyor. Additionally, one or more of theindirect fired kilns in a kiln line may be provided with an agitatorthat vibrates particles of oil shale being processed, thereby topreclude adhesion of the particles of oil shale in the kiln.

Preferably, a plurality of such kiln lines is disposed in convenientproximity in a kiln array. The kiln lines in a kiln array are soconnected to sources of oil shale and fuel as to permit simultaneous,parallel advancement of oil shale through each individual kiln line. Apreferred kiln array thus includes two, three, or even more suchparallel-connected kiln lines.

A kiln line will typically include at least two series-connected,substantially horizontally-disposed kilns, although greater numbers,such as three or more such kilns may be appropriate in specificcircumstances. The initial of the kilns in any kiln line is a pre-heatkiln. In the pre-heat kiln, oil shale granules are dried. The succeedingkilns in the kiln line are indirect-fired from, for example, acorresponding surrounding roasting jacket using the output of a heatsource that employs an appropriate fuel. The output of the heat sourcemay be a combustible gas or a flue gas. In either case, the output ofthe heat source supplied to a roasting jacket is segregated from the oilshale undergoing pyrolysis in the respective kiln with which theroasting jacket is associated. Thus, the contents of the roasting jacketdo not directly contact any of the oil shale granules being processed.

To utilize the full BTU content of combustible gas used in a roastingjacket, any of the combustible gas exhausted from the roasting jacket ofa kiln that succeed the pre-heat kiln is returned to the gasifier forrecycling in the system. Where flue gas is used in a roasting jacket,flue gas exhausted therefrom may be used directly in the pre-heat kilnto dry shale granules, because in the process of drying the oil shale,temperatures are maintained that are too low to cause pyrolysis.

Shale granules pass through the kilns in succession, each kiln beingmaintained at a higher temperature than the preceding kiln.Substantially free of useful hydrocarbons, shale oil granules areexhausted from the kiln line. The shale oil granules thusly exhaustedfrom the kiln line may then advance to a heat extraction unit. Thereheat is recovered from the exhausted oil shale granules as hot air,which is then used in the pre-heat kiln. This optimizes the efficientuse of the heat energy that is imparted to shale granules duringpyrolysis.

In a kiln line that includes three kilns, typically the kilns in orderof increasing temperature are a pre-heat kiln, a first stage pyrolysiskiln, and a second stage pyrolysis kiln. Where larger numbers of kilnsare included in a single kiln line, the additional kilns will beemployed to create additional stages of pyrolysis intermediate the firstand second stages available in a three-kiln kiln line. A kiln line oftwo kilns only will include first a pre-heat kiln followed by a singlepyrolysis kiln, a situation referred subsequently herein as single-stagepyrolysis.

In the pre-heat kiln a temperature is maintained in a range of fromabout 300° F. to about 500° F., more narrowly in a range of from about350° F. to about 450° F., and most specifically at about 400° F. Thesetemperatures are sufficient to drive off moisture (H₂O), drying the oilshale granules that will pass to subsequent kilns of the associated kilnline. The moisture (H₂O) driven off in the pre-heat kiln is returned forfurther use in the gasifier.

In the first stage pyrolysis kiln, true pyrolysis commences. Thetemperature there is maintained in a range of from about 600° F. toabout 850° F., more narrowly in a range of from about 700° F. to about800° F., and most specifically at about 750° F. Initial oil vaporsemerge from the oil shale granules in the first stage pyrolysis kiln.Optimally these may be directed to the refining unit of the systemwithout being allowed to cool.

In the second stage pyrolysis kiln, pyrolysis is completed. Thetemperature there is maintained in a range of from about 950° F. toabout 1100° F., more narrowly in a range of from about 1000° F. to about1075° F., and most specifically at about 1050° F. Under such conditions,even the heaviest of the useful hydrocarbons remaining in the oil shalegranules are extracted as oil vapors. Optimally, these additional oilvapors may be advanced while still hot to the refining unit fordistillation and cracking.

In single-stage pyrolysis, the temperatures maintained in the pre-heatkiln are as stated above, while the temperature in the single pyrolysiskiln is maintained in a range of from about 950° F. to about 1100° F.,more narrowly in a range of from about 1000° F. to about 1075° F., andmost specifically at about 1050° F. Under such conditions, even all ofthe useful hydrocarbons in the oil shale granules are extracted as oilvapors, whether light or heavy.

The teachings of the present invention presented above will beelaborated upon below making specific reference to exemplary embodimentsof the invention depicted in the accompanying figures.

FIG. 1 provides a useful overview of a system and method embodyingteachings of the present invention. Accordingly shown therein are theprimary elements of a system 10 for producing petroleum products 12 froma raw material 14, such as oil shale. To accomplish that objective,system 10 includes a processing sector 16 that will be seen subsequentlyto require for implementation corresponding sets of method steps andcorresponding assemblies of operatively associated processing apparatus.Activity in processing sector 16 is ultimately driven by a heat source18 that optimally involves a fuel distinct from the potentially usefulhydrocarbons in the oil shale being supplied to processing sector 16.

Such a preferred practice distinguishes, however, between using usefulhydrocarbons in the oil shale in the form of oil vapor before that oilvapor is upgraded into petroleum products, and using petroleum productsthat had originally been derived as oil vapor from the pyrolysis of oilshale. Thus while the teachings of the present invention recommend thatthe consumption of useful hydrocarbons in oil shale be minimized, orprecluded entirely, in the operation of a processing sector, such asprocessing sector 16, it is not contrary to those teachings to consumerefined petroleum products, such as petroleum products 12 that areproduced in a processing sector, such as processing sector 16, to drivethat same processing sector.

Processing sector 16 includes a pair of primary sub-sectors. Anextraction sub-sector 20 of processing sector 16 receives raw material14 in the form of oil shale. Useful hydrocarbons in the oil shale areextracted by pyrolysis from the oil shale in extraction sub-sector 20assume the form of oil vapor, which is advanced to a refining sub-sector22 of processing sector 16 for further processing. In refiningsub-sector 22, that oil vapor is upgraded into petroleum products 12,and optimally petroleum products 12 may also there be separated bypredetermined criteria, such as weight, type, and use.

FIG. 1 depicts schematically that extraction sub-sector 20 includes aplurality of kilns 24 and an associated, but not necessarily equal,number of roasting jackets 26 that are operatively associated withcorresponding kilns 24.

While it is contemplated within the teachings of the present inventionthat the number of kilns 24 could be equal to the number of roastingjackets 26, more generally, and preferably, the number of roastingjackets 26 will be at least one less than the number of kilns 24. Thus,it is conceivable that the number of roasting jackets 26 could be one,where the number of kilns 24 is two or greater. It is also contemplatedthat the number of roasting jackets 26 and the number of kilns 24 couldbe equal at two or more, but it is inconsistent with teachings of thepresent invention for the number of kilns 24 to be less than two. Noupper limit other than practicability is contemplated relative to thenumber of roasting jackets 26 or on the number of kilns 24 in a system,such as system 10, configured or operated according to teachings of thepresent invention.

All or some of roasting jackets 26 are supplied with the output of heatsource 18, which may take the form of a combustible gas or a flue gas.Roasting jackets 26 thereby cooperate indirectly with the individualkiln corresponding thereto in maintaining pyrolysis of oil shale beingprocessed in kilns 24. The output from heat source 18 can alternativelybe described as being supplied to all or some of kilns 24. As will beseen subsequently by way of example, kilns 24 are in actuality arrangedin one or more series-connected groupings that already have been, andwill hereinafter be, referred to herein as “kiln lines”. The kiln linesof a typical kiln array are generally fed in parallel with raw material14 in the form of oil shale, as well as with fuel from heat source 18.In this manner, pyrolysis proceeds independently in each kiln line,useful hydrocarbons are extracted from the oil shale advanced througheach of the kiln lines, and spent oil shale is exhausted from each ofthe kiln lines in a from that is substantially free of hydrocarbons.

Optimally, most or even all of the kilns in a kiln line configured andoperated according to teachings of the present invention will besubstantially horizontally-disposed kilns. Such kilns may be strictlyhorizontally-disposed or inclined, stationary or rotatable.

An inclined rotary kiln routinely includes an elongated rotatable drumhaving an input end for receiving oil shale and an output end that isdisposed lower than the input end and through which processed oil shaleis exhausted. The physical and operational parameters associated withthe rotatable drum of each inclined rotary kiln can be variedindependently from one another in order to achieve particular desiredeffects along any portion of the path of advancement of oil shalethrough a given kiln. Thus the length, diameter, thickness, interiorsurface configuration, pitch and rate of rotation of each rotatable drumin such a kiln is a design feature to be arrived at with particularattention to the qualities in the oil shale to be processed, the natureof the fuel to be supplied by heat source 18, and the performancespecification of any of the various apparatus to be employed in refiningsub-sector 22. It is even conceivable that one or more of the rotatabledrums in a kiln may be less than perfectly smoothly cylindrical,possibly assuming a polygonal interior cross section, or a symmetric oran offset conical sector in longitudinal cross section.

As an inclined rotary kiln is rotated about the longitudinal extentthereof, oil shale being processed in the kiln is tumbled longitudinallythrough the kin. This effect may be facilitated by the interiorconstruction of the kiln by, for example, the attachment ofappropriately oriented vanes to the inner surface of the kiln. In analternate from of such a transport for advancing oil shalelongitudinally through a kin during processing of the oil shale in thekiln, a kiln may be provided with an internal conveyor, such as a chainconveyor, a paddle conveyor, or a bucket conveyor.

FIGS. 2A and 2B taken together present a detailed diagrammatic depictionof a first embodiment of the system and the method of FIG. 1. Each willbe discussed in turn below.

In FIG. 2A, what was raw material 14 in FIG. 1 is depicted as a rawmaterial sector 30 of system 10. In raw material sector 30, oil shale 32is supplied to a crusher 34. Processing in crusher 34 converts oil shale32 into crushed oil shale 36 comprised optimally of oil shale granulesof approximately 0.375 inches in diameter. Crushed oil shale 36 is thenadvanced to extraction sub-sector 20 in processing sector 16 of system10.

Also in FIG. 2A, what was heat source 18 in FIG. 1 is depicted as a heatsource sector 40. In heat source sector 40, coal 42 is supplied to apulverizer 44. Processing in pulverizer 44 converts coal 42 intopulverized coal 46 comprised optimally of coal particles of a finenessof about 200 mesh. Pulverized coal 46 is then combined in a solid fuelgasifier 48 with oxygen (O₂), such as oxygen 50, and steam (H₂O), suchas steam 52. In gasifier 48, coal 42 is converted into syngas 54. Slag56 and exhaust gas 58 are byproducts of this process.

All or some of syngas 54 is advanced to extraction sub-sector 20 inprocessing sector 16 of system 10. Thus, the fuel corresponding to heatsource 40 is a hot gaseous fuel. Optionally, a portion of syngas 54 issupplied to a hydrogen separator 60, where hydrogen gas (H₂), such ashydrogen gas 62, is produced. Hydrogen gas 58 has utility in bothsub-sectors of processing sector 16 of system 10. Hydrogen gas 58 may beadvanced to extraction sub-sector 20 in processing sector 16 to enhancethe driving effect of syngas 54 in causing pyrolysis of crushed oilshale 36. Alternatively, or in addition thereto, hydrogen gas 62 may beemployed in the hydrogenation in refining sub-sector 22 that upgradesinto petroleum products oil vapors containing hydrocarbons extractedfrom crushed oil shale 36 in extraction sub-sector 20 of system 10.

Finally, it should be noted that an additional type of fuel suitable forsupply to extraction sub-sector 20 can be a portion of any petroleumproducts, such as petroleum products 12 produced in refining sub-sector22 of processing sector 16 of system 10.

In FIG. 2B, presents a detailed diagrammatic depiction of the variousapparatus and the method steps encompassed by extraction sub-sector 20of processing sector 16 in system 10 shown in FIG. 1. While noadditional detail is provided in FIG. 2B or elsewhere relative to suchaspects of refining sub-sector 22, FIG. 2B does afford a betterunderstanding of the relationship of refining sub-sector 22 to other ofthe elements of system 10 and extraction sub-sector 20 of processingsector 16 in particular.

Thus, it can be seen that in extraction sub-sector 20, crushed oil shale36, syngas 54, and hydrogen gas 62 produced in gasifier 48 of FIG. 2Aare in actuality supplied to a kiln array 70 that is shown to encompassnominally four kiln lines 72, which will be discussed in greater detailsubsequently. In the kilns of kiln lines 72 of kiln array 70, syngas 54and hydrogen gas 62 drive pyrolysis of crushed oil shale 36, producingfrom each of kiln lines 72, or from kiln array 70 taken collectively,extracted useful hydrocarbons in the form of oil vapor 74. As abyproduct of these processes, recyclable gas 76 is produced, butrecyclable gas 76 is advanced to gasifier 48 as shown for reuse there.Also, exhausted from each of kiln lines 72, or from kiln array 70 takencollectively, is oil shale at an elevated temperature reflective of thepyrolysis process. Being also substantially free of useful hydrocarbonsthe oil shale exhausted from kiln array 70 is identified in FIG. 2B ashot spent shale 78.

Also included in extraction sub-sector 20 is a heat extraction unit 80.Heat extraction unit 80 receives hot spent shale 78 exhausted from kilnlines 72 in kiln array 70 and recovers heat 82 therefrom, usually in theform of hot air. Heat 82 recovered in heat extraction unit 80 iscorrespondingly returned to kiln lines 72 in kiln array 70. In each ofkiln lines 72, heat 82 is used to pre-heat crushed oil shale 36 destinedfor eventual pyrolysis therein. As a result of the extraction of heat 82from hot spent shale 78 by heat extraction unit 80, cool spent shale 84is discharged from heat extraction unit 80 for transport to a storagelocation.

Advantageously, refining sub-sector 22 of processing sector 16 islocated in close proximity to kiln lines 72 in kiln array 70. Then oilvapor 74 extracted in kiln lines 72 can reach refining sub-sector 22 ata temperature that is substantially undiminished from the temperatureoil vapor 74 leaves kiln lines 72 of kiln array 70. In refiningsub-sector 22 the commencement of processing of oil vapor 74 at anelevated temperature reduces the amount of fuel, such as hydrogen gas 62shown, that is required to implement upgrading and sorting. As abyproduct of these processes, recyclable gas 76 is also produced asshown in refining sub-sector 22, but recyclable gas 76 is advanced togasifier 48 for reuse there.

FIG. 3 is a detailed diagrammatic depiction of the apparatus and relatedmethodology associated with one exemplary embodiment of a kiln line 72of the type shown in the system and the method of FIG. 2B. Kiln line 72includes a plurality of three series-connected inclined rotary kilns,through which crushed oil shale 36 originally containing potentiallyuseful hydrocarbons is advanced during processing in succession througheach of the kilns and exhausted from kiln line 72 substantially free ofhydrocarbons as hot spent shale 78. Greater numbers of kilns in a kilnline, such as kiln line 72, such as four, five, or even more kilns, areappropriate in specific circumstances. Each successive of the kilns inthe direction of the advancement of crushed oil shale 36 maintains acorresponding oil shale processing environment at a temperature higherthan the temperature of the oil shale processing environment maintainedin the preceding of the kilns.

The initial kiln in kiln line 72 to receive and process crushed oilshale 36 is a pre-heat kiln 90 that is series-connected to the input endof the next kiln in kiln line 72, upstream of that next kiln asdetermined by direction of the advancement of crushed oil shale 36during processing in kiln line 72. That direction of advancement ofcrushed oil shale 36 is indicated in FIG. 3 by the arrows projectingfrom the lower edge of each of the kilns included in FIG. 3. Pre-heatkiln 90 is an inclined rotary kiln that maintains a corresponding oilshale drying environment at a drying temperature T₉₀ at which moisture(H₂O), identified in FIG. 3 as water vapor 92, is removed from crushedoil shale 36. Then crushed oil shale 36 enters the next kiln in kilnline 72. Pre-heat kiln 90 uses heat 82 recovered from hot spent shale 78exhausted from kiln line 72.

The next kiln in kiln line 72 is series-connected to the output end ofpre-heat kiln 90. This second kiln is identified in FIG. 3 as firststage pyrolysis kiln 94. First stage pyrolysis kiln 94 receives forprocessing dried, crushed oil shale 36, which at that stage ofprocessing yet contains all of the potentially useful hydrocarbonstherein. First stage pyrolysis kiln 94 maintains therewithin acorresponding oil shale processing environment in which initialpyrolysis occurs. Accordingly, oil shale processing environmentmaintained in first stage pyrolysis kiln 94 will also be referred as afirst oil shale pyrolysis environment. The temperature of the first oilshale pyrolysis environment is maintained at a first pyrolysistemperature T₉₄. First pyrolysis temperature T₉₄ is greater than dryingtemperature T₉₀ maintained in pre-heat kiln 90 by approximately 300° F.,or more.

This is accomplished by the operative association of a first roastingjacket 96 with first stage pyrolysis kiln 94. First roasting jacket 96is supplied as shown with sufficient syngas 54 to indirectly maintainthe requisite first oil shale processing environment in first stagepyrolysis kiln 94. Any components of syngas 54 that are incompletelycombusted in first roasting jacket 96 is withdrawn as fuel gas exhaust102 and forwarded as a component of recyclable gas 76 to gasifier 48 asshown.

As a result, first stage pyrolysis kiln 94 produces first stage oilvapor 98 that contains an initial quantity of the useful hydrocarbons indried crushed oil shale 36. First stage oil vapor 98 is a component ofoil vapor 74 that is forwarded to refining sub-sector 22 for upgradinginto petroleum products 12. Valving 100 in the path of flow of firststage oil vapor 98 permits the type or types of oil vapor reachingrefining sub-sector 22 to be controlled toward optimizing the operationthereof.

The next kiln in kiln line 72 is series-connected to the output end offirst stage pyrolysis kiln 94. This second kiln is identified in FIG. 3as second stage pyrolysis kiln 104. Second stage pyrolysis kiln 104receives for processing dried and partially exhausted crushed oil shale36, which at that stage of processing yet contains some, particularlythe heavier, of the potentially useful hydrocarbons therein. Secondstage pyrolysis kiln 104 maintains therewithin a corresponding oil shaleprocessing environment in which additional pyrolysis occurs.Accordingly, the oil shale processing environment maintained in secondstage pyrolysis kiln 104 will also be referred as a second oil shalepyrolysis environment. The temperature of the second oil shale pyrolysisenvironment is maintained at a second pyrolysis temperature T₁₀₄. Secondpyrolysis temperature T₁₀₄ is greater than first pyrolysis temperatureT₉₄ maintained in first stage pyrolysis kiln 94 by approximately 300°F., or more.

This is accomplished by the operative association of a second roastingjacket 106 with second stage pyrolysis kiln 104. Second roasting jacket106 is supplied as shown with sufficient syngas 54 supplemented asdesired by hydrogen gas 62 to indirectly maintain the requisite secondoil shale processing environment in second stage pyrolysis kiln 104. Anycomponents of syngas 54 or hydrogen gas 62 that are incompletelycombusted in second roasting jacket 106 is withdrawn as fuel gas exhaust102 and forwarded as a component of recyclable gas 76 to gasifier 48 asshown.

As a result, second stage pyrolysis kiln 104 produces second stage oilvapor 108 that contains an additional quantity of the usefulhydrocarbons in dried and partially exhausted crushed oil shale 36.Second stage oil vapor 108 is a component of oil vapor 74 that isforwarded to refining sub-sector 22 for upgrading into petroleumproducts 12. Valving 100 in the path of flow of second stage oil vapor98 permits the type or types of oil vapor reaching refining sub-sector22 to be controlled toward optimizing the operation thereof.

Ranges of temperatures in typical kilns, such as first stage pyrolysiskiln 94 and second stage pyrolysis kiln 104, have already been providedabove. Each included a corresponding optimum temperature correspondingto the respective pyrolysis temperatures named above. Accordingly, in athree-kiln line, such as kiln line 73 shown in FIG. 3, first pyrolysistemperature T₉₄ would be about 750° F. and second pyrolysis temperatureT₁₀₄ would be about 1050° F.

Where larger numbers of kilns are included in a single kiln line, theadditional kilns will be employed to create additional stages ofpyrolysis intermediate the first and second stages available in athree-kiln kiln line. Thus in a four-kiln kiln line, the temperaturesmaintained in the three pyrolysis kilns would be respectively along thepath of advancing oil shale about 650° F., about 850° F., and about1050° F. In a five-kiln kiln line, the temperatures maintained in thefour pyrolysis kilns would be respectively along the path of advancingoil shale about 600° F., about 800° F., about 950° F., and about 1050°F.

FIGS. 4A and 4B taken together present a detailed diagrammatic depictionof yet a second embodiment of the system 110 and the method of FIG. 1.Each will be discussed in turn below.

In FIG. 4A, what was raw material 14 in FIG. 1 is depicted as a rawmaterial sector 114 of system 110, and what was extraction sub-sector 20in processing sector 16 in FIG. 1 is identified as an extractionsub-sector 120 in a processing sector 126 that does not appear in FIG.4A, but that is shown in FIG. 4B. In raw material sector 114, oil shale32 is supplied to a crusher 34. Processing in crusher 34 converts oilshale 32 into crushed oil shale 36 comprised optimally of oil shalegranules of approximately 0.375 inches in diameter. Crushed oil shale 36is then advanced to extraction sub-sector 120 in processing sector 126of system 110.

Also in FIG. 4A, what was heat source 18 in FIG. 1 is depicted as a heatsource sector 130 of system 110. In heat source sector 130, natural gas132 is supplied to a burner 134. Processing in burner 134 convertsnatural gas 132 into hot flue gas 136 at a temperature in a range offrom about 750° F. to about 2000° F., more narrowly in a range of fromabout 1000° F. to about 1300° F., and most specifically at about 1100°F. Flue gas 136 is advanced to extraction sub-sector 120 in processingsector 126 of system 110. Thus, the output of heat source sector 130 ishot flue gas 136.

Heat 138 from the combustion of natural gas 132 in burner 134 is used bya heat exchanger 140 to preheat to a range of about 1800° F. to about2000° F. a sweep gas 142 that is capable of inhibiting combustion in anoil shale pyrolysis environment and when pressurized, therefore, is alsocapable of entraining for removal from oil shale pyrolysis environmenthydrocarbons extracted from the oil shale being processed therein.Nitrogen (N₂) serves adequately as such a sweep gas

FIG. 4B, presents a detailed diagrammatic depiction of the variousapparatus and the method steps encompassed by extraction sub-sector 120of processing sector 126 in system 110. What was refining sub-sector 22of system 10 in FIG. 1 is depicted as refining sub-sector 144 of system110 in FIG. 4B. While no additional detail is provided in FIG. 4B orelsewhere relative to such aspects of refining sub-sector 144, FIG. 4Bdoes afford a better understanding of the relationship of refiningsub-sector 144 to other of the elements of system 110 and extractionsub-sector 120 of processing sector 126 in particular.

Thus, it can be seen that in extraction sub-sector 120, crushed oilshale 36, hot flue gas 136 from burner 134, and sweep gas 142 are inactuality supplied to a kiln array 150 that is shown to encompassnominally four kiln lines 152, which will be discussed in greater detailsubsequently. In the kilns of kiln lines 152 of kiln array 150, flue gas136 drives pyrolysis of crushed oil shale 36, producing from each ofkiln lines 152, or from kiln array 150 taken collectively, extracteduseful hydrocarbons in the form ultimately of oil 154. Exhausted fromeach of kiln lines 152, or from kiln array 150 taken collectively, isoil shale at a temperature of about 1000° F. that is substantially freeof useful hydrocarbons, which is identified in FIG. 4B as spent shale158.

Refining sub-sector 144 of processing sector 126 is located in closeproximity to kiln lines 152 in kiln array 150. Then oil 154 extracted inkiln lines 152 can reach refining sub-sector 144 without substantialcooling. In refining sub-sector 144 the commencement of processing ofoil 154 at an elevated temperature reduces the amount of fuel, such ashydrogen gas 162 shown, that is required to implement upgrading andsorting.

FIG. 5 is a detailed diagrammatic depiction of the apparatus and relatedmethodology associated with one exemplary embodiment of a kiln line 152of the type shown in the system and the method of FIG. 4B. Kiln line 152includes a plurality of two series-connected, substantiallyhorizontally-disposed kilns, through which crushed oil shale 36originally containing potentially useful hydrocarbons is advanced duringprocessing in succession through each of the kilns and exhausted fromkiln line 152 substantially free of hydrocarbons as spent shale 158.Greater numbers of kilns in a kiln line, such as kiln line 152, such asthree or more kilns, are appropriate in specific circumstances. Eachsuccessive of the kilns in the direction of the advancement of crushedoil shale 36 maintains a corresponding oil shale processing environmentat a temperature higher than the temperature of the oil shale processingenvironment maintained in the preceding of the kilns.

The initial kiln in kiln line 152 to receive and process crushed oilshale 36 is a pre-heat kiln 170 that is series-connected to the inputend of the next kiln in kiln line 152, upstream of that next kiln asdetermined by direction of the advancement of crushed oil shale 36during processing in kiln line 152. That direction of advancement ofcrushed oil shale 36 is indicated in FIG. 5 by the arrows projectingfrom the lower edge of each of the kilns included in FIG. 5. Pre-heatkiln 170 is a substantially horizontally-disposed kiln that maintains acorresponding oil shale drying environment at a drying temperature T₉₀at which moisture (H₂O), identified in FIG. 5 as water vapor 172, isremoved from crushed oil shale 36. Then crushed oil shale 36 enters thenext kiln in kiln line 152. Pre-heat kiln 170 uses heat 82 from hot fluegas exhaust 174 that is discharged from kiln line 152 after drivingpyrolysis therein.

Located within pre-heat kiln 170 is a pre-heat oil shale transport 176that advances crushed oil shale 36 longitudinally through pre-heat kiln170 during the processing of crushed oil shale 36 therein. Pre-heat oilshale transport 176 can take several forms from that of an auger or aconveyor to any means for rotating pre-heat kiln 170 about thelongitudinal extent thereof in such a manner as to tumble crushed oilshale 36 longitudinally through pre-heat kiln 170. The effectiveness ofthe later from of pre-heat oil shale transport 176 is enhanced whenpre-heat kiln 170 is inclined.

The next kiln in kiln line 152 is series-connected to the output end ofpre-heat kiln 170. This second kiln is identified in FIG. 5 as apyrolysis kiln 180. Pyrolysis kiln 180 receives for processing dried,crushed oil shale 36, which at that stage of processing yet contains allof the potentially useful hydrocarbons therein. Pyrolysis kiln 180maintains therewithin a corresponding oil shale processing environmentin which full pyrolysis occurs. Accordingly, oil shale processingenvironment maintained in pyrolysis kiln 180 will also be referred as afull oil shale pyrolysis environment. The temperature of the fill oilshale pyrolysis environment is maintained at a full pyrolysistemperature T₁₈₀. Full pyrolysis temperature T₁₈₀ is greater than dryingtemperature T₁₇₀ maintained in pre-heat kiln 170 by approximately 300°F., or more.

This is accomplished by the operative association of a roasting jacket182 with pyrolysis kiln 180. First roasting jacket 182 is supplied asshown with sufficient flue gas 136 to indirectly maintain the requisitefull oil shale processing environment in pyrolysis kiln 180. Flue gas136 exiting roasting jacket 182 is forwarded to pre-heat kiln 170 asshown.

Located within pyrolysis kiln 180 is a pyrolysis oil shale transport 190that advances dried crushed oil shale 36 longitudinally throughpyrolysis kiln 180 during the processing of dried crushed oil shale 36therein. Pyrolysis oil shale transport 190 can take several forms fromthat of an auger or a conveyor to any means for rotating pyrolysis kiln180 about the longitudinal extent thereof in such a manner as to tumbledried crushed oil shale 36 longitudinally through pyrolysis kiln 180.The effectiveness of the later from of pyrolysis oil shale transport 190is enhanced when pyrolysis kiln 180 is inclined.

Pyrolysis kiln 180 produces entrained oil vapor 184 that contains all ofthe useful hydrocarbons in dried crushed oil shale 36 carried in astream of sweep gas 142. Entrained oil vapor 184 is advanced to acondenser separator 186, where by cooling entrained oil vapor 184, oil154 condenses therefrom, leaving a residue of light gaseous hydrocarbons188, which are advanced for combustion to burner 134. Oil 154 isforwarded to refining sub-sector 144 for upgrading into petroleumproducts 12.

Operatively associated with pyrolysis kiln 180 is an agitator 192 thatvibrates particles of dried oil shale (36) being processed in pyrolysiskiln 180, thereby to preclude adhesion of particles of dried oil shale(36) during processing in pyrolysis kiln 180. Agitator 192 does so bydirecting sound at high frequencies into pyrolysis kiln 180. Asatisfactory device for serving as such an agitator is any of theaudiosonic acoustic horns identified by Model Nos. PAS-420, PAS-350,PAS-230, PAS-75, and PAS-60 available from Primasonics InternationalLimited of Cumbria, England. These devices emit sound waves an intensitylevel of about 150 decibels in a range of frequencies from about 60hertz to about 420 hertz.

The inventive technology also includes corresponding methods.

Accordingly, broadly such a method for producing petroleum products fromoil shale includes the steps of drying oil shale containing hydrocarbonsin a substantially horizontally-disposed pre-heat kiln to produce dryoil shale, while transporting the oil shale containing hydrocarbons fromthe input end to the output end of the pre-heat kiln. Dry oil shale fromthe output end of the pre-heat kiln is then transferred to the input endof a substantially horizontally-disposed pyrolysis kiln. This isfollowed by the steps of indirectly heating the dry oil shale in thepyrolysis kiln to thereby extract hydrocarbons from that dry oil shale,while transporting the dry oil shale from the input end to the outputend of the pyrolysis kiln.

The inventive method may also include the steps of heating a sweep gascapable of inhibiting combustion in the pyrolysis kiln, and forcing theheated sweep gas through the pyrolysis kiln, thereby to entrain in thesweep gas and remove from the pyrolysis kiln hydrocarbons extracted insaid pyrolysis kiln from the dry oil shale. It is also advantageous tovibrate particles of dry oil shale in the pyrolysis kiln to precludeadhesion of the particles of dry oil shale during processing in saidpyrolysis kiln.

One specific embodiment of the inventive method for producing petroleumproducts from oil shale includes the step of heating oil shalecontaining hydrocarbons in an inclined rotary pre-heat kiln to producedry oil shale. This is followed by the step of extracting initialhydrocarbons from the dry oil shale in an inclined rotary firstpyrolysis kiln that is series-connected to the output end of thepre-heat kiln. Additional hydrocarbons are extracted from the oil shaleprocessed through the first pyrolysis kiln using an inclined rotarysecond pyrolysis kiln that is series-connected to the output end of thefirst pyrolysis kiln.

The heating of the pre-heat kiln is conducted using heat recovered fromoil shale processed through the second pyrolysis kiln. Alternatively,where flue gas is produced by the heat source of the system for use todrive pyrolysis, exhausted flue gas from each pyrolysis kiln may be usedin direct contact with the oil shale in the pre-heat kiln to effectdehydration.

All the steps of extracting hydrocarbons from dry oil shale areconducted by indirectly roasting the contents of respective pyrolysiskilns using the output of a heat source that employs a fuel distinctfrom hydrocarbons in oil shale being processed. To obtain output of theheat source, the inventive method may include the steps of separatinghydrogen gas from other gasses, and employing that hydrogen as acombustible gas to drive pyrolysis. Alternatively or in additionthereto, the inventive method may include the steps of gasifying a solidinto a combustible gas, and employing that combustible gas to drivepyrolysis. Yet further, to obtain the output of the heat source, theinventive method may include the steps of burning a combustible gas,such as natural gas or even syngas to produce a hot flue gas, andemploying that flue gas to drive pyrolysis.

The inventive method may also include the additional step of refiningindividually or together the hydrocarbons extracted, respectively, inthe first and second pyrolysis kilns. This is accomplished by upgradingeither or both of those groups of extracted hydrocarbons into petroleumproducts and then separating the petroleum products by predeterminedcriteria.

The foregoing description of the invention has been presented for thepurposes of promoting clarity and conveying a complete understanding ofthe present invention. The description thus presented is not intended tocause the present invention to be limited merely to the preciseembodiments thereof disclosed. Various modifications of thoseembodiments are possible that remain nonetheless within the scope andequivalence properly to be accorded to the appended claims.

1. A system for producing petroleum products from oil shale, said systemcomprising: (a) a kiln line comprising series-connected, substantiallyhorizontally-disposed, elongated kilns, oil shale containinghydrocarbons being processed in individual of said kilns in successionand being exhausted from said kiln line substantially free ofhydrocarbons, each successive of said kilns in the direction of theprocessing of the oil shale maintaining a corresponding oil shaleprocessing environment at a temperature higher than the temperature ofthe oil shale processing environment maintained in the preceding of saidkilns, and at least one of said kilns being an indirect-fired kiln; and(b) a heat source employing a fuel distinct from hydrocarbons in the oilshale being processed in said kiln line, the output of said heat sourcebeing supplied to said kiln line to drive pyrolysis and to extracthydrocarbons from the oil shale processed through said kiln line.
 2. Asystem as recited in claim 1, wherein said output of said heat sourcecomprises combustible gas.
 3. A system as recited in claim 2, whereinsaid fuel employed by said heat source comprises a solid fuel.
 4. Asystem as recited in claim 3, wherein said heat source comprises agasifier of said solid fuel, the yield produced by said gasifiercorresponding to said output of said heat source.
 5. A system as recitedin claim 4, wherein said gasifier is located proximate to said kilnline, whereby said yield produced by said gasifier reaches said kilnline at a temperature substantially undiminished from the temperature ofsaid yield when said yield leaves said gasifier.
 6. A system as recitedin claim 4, wherein said gasifier produces syngas from coal.
 7. A systemas recited in claim 2, wherein said heat source comprises a hydrogenseparator.
 8. A system as recited in claim 1, wherein said heat sourcecomprises a burner of combustible gas, flue gas from said burnercorresponding to said output of said heat source.
 9. A system as recitedin claim 8, wherein said combustible gas comprises natural gas.
 10. Asystem as recited in claim 8, wherein said combustible gas comprisessyngas.
 11. A system as recited in claim 10, wherein said syngas isproduced by said heat source from a solid fuel.
 12. A system as recitedin claim 8, wherein said heat source further comprises a heat exchangerassociated with said burner, said heat exchanger using heat generated insaid burner to preheat a sweep gas employed in contact with the oilshale being processed in said indirect-fired kiln in said kiln line. 13.A system as recited in claim 8, wherein flue gas exhausted from saidindirect-fired kiln is used to dry oil shale entering saidindirect-fired kiln.
 14. A system as recited in claim 1, furthercomprising an oil shale transport associated with a kiln in said kilnline, said transport advancing oil shale longitudinally through said kinduring processing of the oil shale in said kiln.
 15. A system as recitedin claim 14, wherein said transport comprises an auger positioned withinsaid kiln.
 16. A system as recited in claim 14, wherein said transportcomprises a conveyor positioned within said kiln.
 17. A system asrecited in claim 16, wherein said conveyor comprises a chain conveyor.18. A system as recited in claim 16, wherein said conveyor comprises apaddle conveyor.
 19. A system as recited in claim 16, wherein saidconveyor comprises a bucket conveyor.
 20. A system as recited in claim14, wherein said transport comprises means for rotating said kiln aboutthe longitudinal extent thereof and tumbling oil shale being processedin said kiln longitudinally through said kin.
 21. A system as recited inclaim 20, wherein said kiln is inclined downwardly along thelongitudinal extent thereof from an input end to an output end of saidkiln, oil shale being presented for processing at said input end of saidkiln and being discharged following processing from said output end ofsaid kiln.
 22. A system as recited in claim 1 wherein said kilns in saidkiln line are rotary kilns.
 23. A system as recited in claim 1, whereinsaid kilns in said kiln line are stationary kilns.
 24. A system asrecited in claim 1, wherein said kilns in said kiln line are inclinedkilns.
 25. A system as recited in claim 24, wherein said inclined kilnsare rotary kilns.
 26. A system as recited in claim 1, wherein said kilnsin said kiln line are strictly horizontally-disposed kilns.
 27. A systemas recited in claim 26, wherein said strictly horizontally-disposedkilns are stationary kilns.
 28. A system as recited in claim 1, furthercomprising a source of pressurized sweep gas, said sweep gas inhibitingcombustion in said indirect-fired kiln of said kiln line and entrainingfor removal from said indirect-fired kiln hydrocarbons extracted fromthe oil shale being processed therein.
 29. A system as recited in claim28, wherein said sweep gas is heated prior to entry into saidindirect-fired kiln.
 30. A system as recited in claim 1, furthercomprising an agitator associated with said indirect-fired kiln of saidkiln line, said agitator vibrating particles of oil shale beingprocessed in said indirect-fired kiln, thereby to preclude adhesion ofsaid particles of oil shale during processing in said indirect-firedkiln.
 31. A system as recited in claim 30, wherein said agitator directssound into said indirect-fired kiln.
 32. A system as recited in claim 1,further comprising a refining unit, said refining unit receivingextracted hydrocarbons from the oil shale processed through said kilnline, upgrading said extracted hydrocarbons into petroleum products, andseparating said petroleum products by predetermined criteria.
 33. Asystem as recited in claim 32, wherein said refining unit is locatedproximate to said kiln line, whereby said extracted hydrocarbons reachsaid refining unit at a temperature substantially undiminished from thetemperature of said extracted hydrocarbons when said extractedhydrocarbons leave said kiln line.
 34. A system as recited in claim 32,wherein said system further comprises a hydrogen separator, hydrogen gasfrom said hydrogen separator being employed in said refining unit.
 35. Asystem as recited in claim 32, wherein said fuel corresponding to saidheat source comprises selected of said petroleum products separated insaid refining unit.
 36. A system as recited in claim 1, comprising aplurality of said kiln lines, said plurality of kiln lines beingparallel-connected relative to each other, whereby oil shale containinghydrocarbons is processed simultaneously through individual of said kilnlines and is exhausted therefrom substantially free of hydrocarbons. 37.A system as recited in claim 1, further comprising a heat extractionunit, said heat extraction unit receiving exhausted oil shale from saidkiln line and recovering heat therefrom, said heat recovered in saidheat extraction unit being returned to said kiln line.
 38. A system forproducing petroleum products from oil shale, said system comprising: (a)a first inclined rotary kiln, said first inclined rotary kiln receivingfor processing oil shale containing hydrocarbons and maintainingtherewithin a corresponding first oil shale processing environment at afirst temperature; (b) a first roasting jacket operatively associatedwith said first kiln and supplied with sufficient heat to indirectlymaintain said first oil shale processing environment in said firstinclined rotary kiln; (c) a second inclined rotary kiln series-connectedto the output end of said first inclined rotary kiln, said secondinclined rotary kiln receiving for further processing oil shaleprocessed through said first inclined rotary kiln and maintainingtherewithin a corresponding second oil shale processing environment at asecond temperature greater than said first temperature in said firstinclined rotary kiln; (d) a second roasting jacket operativelyassociated with said second inclined rotary kiln and supplied withsufficient heat to indirectly maintain said second oil shale processingenvironment in said second inclined rotary kiln; and (e) a heat sourcecomprising a fuel distinct from hydrocarbons in oil shale, said fuelcorresponding to said heat source being supplied to said first andsecond roasting jackets, thereby to extract hydrocarbons from oil shaleprocessed through said first and second inclined rotary kilns,respectively.
 39. A system as recited in claim 38, wherein initialpyrolysis occurs in said first oil shale processing environment in saidfirst inclined rotary kiln, and additional pyrolysis occurs in saidsecond oil shale processing environment in said second inclined rotarykiln.
 40. A system as recited in claim 39, wherein said firsttemperature in said first inclined rotary kiln is about 650° Fahrenheit,and said second temperature in said second inclined rotary kiln is about1050° Fahrenheit.
 41. A system as recited in claim 38, furthercomprising a refining unit located proximate to said first and secondinclined rotary kilns, said refining unit receiving extractedhydrocarbons from the oil shale processed through said first and secondinclined rotary kilns, upgrading said extracted hydrocarbons intopetroleum products, and separating said petroleum products bypredetermined criteria, said extracted hydrocarbons reaching saidrefining unit at a temperature substantially undiminished from thetemperature of said extracted hydrocarbons when said extractedhydrocarbons leave said first and second inclined rotary kilns,respectively.
 42. A system as recited in claim 41, wherein said refiningunit upgrades said extracted hydrocarbons from said first kilnindependently of said extracted hydrocarbons from said second kiln. 43.A system as recited in claim 41, further comprising a pre-heat kilnseries-connected to the input end of said first inclined rotary kilnupstream of said first inclined rotary kiln in the direction of theadvancement of the oil shale during processing in said first and secondinclined rotary kilns.
 44. A system as recited in claim 43, wherein saidpre-heat kiln comprises an inclined rotary kiln maintaining acorresponding oil shale drying environment in which moisture is removedfrom oil shale before the oil shale enters said first inclined rotarykiln.
 45. A system as recited in claim 43, wherein said pre-heat kilnuses heat recovered from oil shale processed through said secondinclined rotary kiln.
 46. A system for producing petroleum products fromoil shale, said system comprising: (a) a pre-heat kiln, said pre-heatkiln receiving for processing oil shale containing hydrocarbons andmaintaining a corresponding oil shale drying environment whereinmoisture is removed from the oil shale received by said pre-heat kiln;(b) an indirect-fired substantially horizontally-disposed pyrolysis kilnseries-connected to the output end of said pre-heat kiln, said pyrolysiskiln receiving for further processing oil shale processed through saidpre-heat kiln and maintaining a corresponding pyrolysis environmentwherein hydrocarbons are removed from the oil shale received by saidpyrolysis kiln, said pyrolysis environment in said pyrolysis kiln beinghotter than said oil shale drying environment in said pre-heat kiln; (c)a source of pressurized sweep gas, said sweep gas inhibiting combustionin said pyrolysis kiln line and entraining for removal from saidpyrolysis kiln hydrocarbons extracted from the oil shale being processedtherein; and (d) a heat source, the output of said heat source beingsupplied to said pyrolysis kiln thereby to maintain said pyrolysisenvironment.
 47. A system as recited in claim 46, wherein said heatsource comprises a burner of combustible gas, flue gas from said burnercorresponding to said output of said heat source.
 48. A system asrecited in claim 47, wherein flue gas exhausted from said pyrolysis kilnis used in said pre-heat kiln to maintain oil shale drying environment.49. A system as recited in claim 47, wherein said heat source furthercomprises a heat exchanger associated with said burner, said heatexchanger using heat generated in said burner to preheat said sweep gas.50. A system as recited in claim 46, further comprising a pre-heat oilshale transport associated with said pre-heat kiln, said pre-heat oilshale transport advancing oil shale longitudinally through said pre-heatkiln during processing of the oil shale in said pre-heat kiln.
 51. Asystem as recited in claim 46, further comprising a pyrolysis oil shaletransport associated with said pyrolysis kiln, said pyrolysis oil shaletransport advancing oil shale longitudinally through said pyrolysis kilnduring processing of the oil shale in said pyrolysis kiln.
 52. A systemas recited in claim 46, further comprising a roasting jacket operativelyassociated with said kilns in said pyrolysis, said roasting jacket beingsufficiently supplied with flue gas from said heat source to cooperateindirectly with said pyrolysis kiln in maintaining pyrolysis of the oilshale advanced therethrough.
 53. A system as recited in claim 46,wherein said sweep gas comprises nitrogen.
 54. A method for producingpetroleum products from oil shale, the method comprising the steps: (a)drying oil shale containing hydrocarbons in a substantiallyhorizontally-disposed pre-heat kiln to produce dry oil shale; (b)transporting oil shale containing hydrocarbons from the input end to theoutput end of said pre-heat kiln during said step of drying; (c)transferring dry oil shale from said output end of said pre-heat kiln tothe input end of a substantially horizontally-disposed pyrolysis kiln;(d) indirectly heating said dry oil shale in said pyrolysis kiln tothereby extract hydrocarbons from said dry oil shale in said pyrolysiskiln; and (d) transporting dry oil shale from the input end to theoutput end of said pyrolysis kiln during said step of indirectlyheating.
 55. A method as recited in claim 54, further comprising thesteps: (a) heating a sweep gas capable of inhibiting combustion in saidpyrolysis kiln; and (b) forcing said heated sweep gas through saidpyrolysis kiln, thereby to entrain in said sweep gas and remove fromsaid pyrolysis kiln hydrocarbons extracted in said pyrolysis kiln fromsaid dry oil shale.
 56. A method as recited in claim 54, furthercomprising the step of vibrating particles of dry oil shale in saidpyrolysis kiln to preclude adhesion of said particles of dry oil shaleduring processing in said pyrolysis kiln.
 57. A method as recited inclaim 54, wherein said step of transporting oil shale containinghydrocarbons comprises the step of rotating said pre-heat kiln to tumblesaid oil shale containing hydrocarbons from the input end to the outputend of said pre-heat kiln.
 58. A method as recited in claim 54, whereinsaid step of transporting dry oil shale comprises the step of rotatingsaid pre-heat kiln to tumble said dry oil shale from the input end tothe output end of said pyrolysis kiln.
 59. A method as recited in claim54, wherein said step of transporting oil shale containing hydrocarbonscomprises the step of using a conveyor to advance said oil shalecontaining hydrocarbons from the input end to the output end of saidpre-heat kiln.
 60. A method as recited in claim 54, wherein said step oftransporting dry oil shale comprises the step of using a conveyor toadvance said dry oil shale from the input end to the output end of saidpyrolysis kiln.
 61. A method as recited in claim 54, wherein said stepof drying is conducted using heat recovered from oil shale processedthrough said pyrolysis kiln.
 62. A method as recited in claim 54,wherein said step of drying is conducted using heat exhausted from saidpyrolysis kiln.
 63. A method as recited in claim 54, further comprisingthe step of refining said hydrocarbons extracted in said pyrolysis kilnby upgrading said hydrocarbons into petroleum products and separatingsaid petroleum products by predetermined criteria.
 64. A method asrecited in claim 54, wherein said step of indirectly heating isconducted using the output of a heat source employing a fuel distinctfrom hydrocarbons in the oil shale being processed in said pyrolysiskiln.
 65. A method as recited in claim 64, further comprising the stepsof: (a) separating hydrogen gas from other gasses; and (b) employingsaid hydrogen gas from said step of separating as said output of saidheat source.
 66. A method as recited in claim 64, further comprising thesteps of: (a) gasifying a solid into a combustible gas; and (b)employing said combustible gas from said step of gasifying as saidoutput of said heat source.
 67. A method as recited in claim 64, furthercomprising the steps of: (a) burning a natural gas to produce flue gas;and (b) employing said flue gas from said step of burning as said outputof said heat source.